Following are a number of excerpts from an Anonymous Treatise on Re-baptism (254-257 A.D.), which seem to convey early disagreement with the idea that baptism is necessary for salvation. The first objection from the author concerns people who heard the gospel and never had a chance to get baptized upon becoming a Christian:
"And what wilt thou determine against the person of him who hears the word, and haply taken up in the name of Christ, has at once confessed, and has been punished before it has been granted him to be baptized with water? Wilt thou declare him to have perished because he has not been baptized with water? Or, indeed, wilt thou think that there may be something from without that helps him to salvation, although he is not baptized with water? They thinking him to have perished will be opposed by the sentence of the Lord, who says “Whosoever shall confess me before men, him will I also confess before my Father which is in heaven;” because it is no matter whether he who confesses for the Lord is a hearer of the word or a believer, so long as he confesses that same Christ whom he ought to confess...therefore nobody can confess Christ without His name, nor can the name of Christ avail any one for confession without Christ Himself."
The author references Jesus' promise in Matthew 10:32. This would suggest that confession of faith is sufficient for salvation, regardless of baptismal status.
The author of this treatise also uses the example of the apostles and their betrayal of Christ as an argument against baptismal regeneration:
"...but all the disciples, to whom, though already baptized, the Lord afterwards says, that “all ye shall be offended in me,” all of whom, as we observe, having amended their faith, were baptized after the Lord’s resurrection with the Holy Spirit…the baptism of water, which is of less account provided that afterwards a sincere faith in the truth is evident in the baptism of the Spirit, which undoubtedly is of greater account."
The example of the apostles, who despite being baptized, abandoned Jesus but later received the Holy Spirit, is used to argue that the baptism of the Spirit holds greater significance than water baptism. This implies that a sincere faith and the reception of the Holy Spirit are more crucial for salvation than the physical act of being baptized with water.
The author even goes to distinguish between the baptism of water and the baptism of the Holy Spirit:
"Which Spirit also filled John the Baptist even from his mother’s womb; and it fell upon those who were with Cornelius the centurion before they were baptized with water. Thus, cleaving to the baptism of men, the Holy Spirit either goes before or follows it; or failing the baptism of water, it falls upon those who believe."
He notes instances where the Holy Spirit was bestowed without prior water baptism (e.g., John the Baptist and those with Cornelius). This would suggest that the Holy Spirit can precede or follow water baptism, or even occur in the absence of water baptism, emphasizing faith as the key to receiving the Holy Spirit. Consider this excerpt from the treatise:
"And there will be no doubt that men may be baptized with the Holy Ghost without water, as thou observest that these were baptized before they were baptized with water; that the announcements of both John and of our Lord Himself were satisfied, forasmuch as they received the grace of the promise both without the imposition of the apostle’s hands and without the laver [baptismal font], which they attained afterwards. And their hearts being purified, God bestowed upon them at the same time, in virtue of their faith, remission of sins; so that the subsequent baptism conferred upon them this benefit alone, that they received also the invocation of the name of Jesus Christ, that nothing might appear to be wanting to the integrity of their service and faith."
The last excerpt underscores the belief that people can be saved through the Holy Spirit without being baptized with water. Water baptism is seen as supplementary, conferring the invocation of Jesus' name. It is not seen as necessary for the remission of sins or salvation.